1. Field of the Invention
The present invention is directed to apparatus for coupling railway cars, and more particularly to E-type and F-type yokes that are constructed to be lighter in weight than current yokes and to provide improved wear resistance.
2. Description of Related Art
It is common practice in the railroad industry to use coupling components to secure adjacent rail cars together, in particular, freight cars. In general, two adjacent freight cars are joined by heavy shafts extending from each car, known as couplers. The couplers are installed on yokes that are mounted on the underside of the car. Railway couplers, particularly those utilized for railway freight cars or vehicles, have a coupler body which is an integral casting of a coupler head and a shank. The head of the shank may be an AAR Standard Type “E” or “F” Coupler Head. The head also carries a knuckle and includes a lock, a thrower, a pivot pin and an articulated lock assembly. Couplers generally carry a knuckle which is pivotally mounted on the coupler head and is designed to engage with another knuckle carried on an adjacent coupler or another car.
The coupler is made from a casting formed from low alloy steel. Although there are AAR standards for couplers, the length of the shank from the butt end of the coupler to the location where the shank joins the head may vary. The coupler is designed to be installed on a draft yoke of a railway vehicle. In the case of the type F coupler shank, the butt end of the coupler shank is a spherical surface and bears against the face of the front follower plate mounted within the yoke. The coupler is pivotally mounted on a yoke with a pin that joins the coupler to the vehicle's yoke. Generally, each coupler is engaged with a yoke housing a shock-absorbing element referred to as the draft gear. The type-E and type-F couplers are the standard couplers for railway freight cars. As a result of implementation of AAR standards and specifications for production of couplers, such as a type-E coupler, the standard railway car couplers are completely interchangeable, regardless of the manufacturer. In addition, adherence to a standard also promotes uniformity among manufacturers products, so that couplers from any one manufacturer are to able to be readily joined to couplers from any other domestic manufacturer. The Association of American Railroads (“AAR”) has adopted standards for railway couplers, which provide specific geometry and dimensions that allow the coupler to receive standard knuckles that are pivotally carried on the coupler to couple with a knuckle on a coupler of an adjacent railway car. The knuckle must be allowed to freely operate when coupling and uncoupling railway cars. In order to determine whether a coupler meets the AAR standards, gauges may be used, which are applied to the coupler to verify that the coupler dimensions or parameters are within an allowable variation or tolerance range.
Each coupler is engaged with a yoke housing a shock-absorbing element referred to as the draft gear. Conventionally, the yoke is an elongated structure having two side sections extending from and joined by a tail portion. The side sections are also known and referred to as “straps”. The side sections or straps are joined at the opposite end by a head portion where the yoke is joined to the coupler with a securing component, such as a key or pin. The yoke generally has a pocket formed by the straps and a rear wall, and a draft gear is positioned between the straps of the yoke, and between the tail portion and the head portion. The best-known yokes are the E-type and F-type. The E-type yoke is governed by AAR standards that include the AAR S-143 Standard, SY 40AE, Y40 or YS93AE, for a 24⅝ inch gear pocket, although there are some tolerances that the pocket may have, as permitted by the standards. A typical E-type yoke has straps that are 5 inches. The F-type yoke is governed by the S-149 standard and the Y45 standard. Although there are other differences between E-type and F-type yokes, a primary difference is the design and orientation of the pin or key used to join the coupler to the yoke.
Typical yokes contain apertures in the yoke head portion, which also may be known as the key slots or pin bores by which a coupler is joined to the yoke with the installation of a key or pin through the slot or bore to connect the yoke and coupler. Adjacent railcars, when coupled together and in motion, place tension on the yoke and compressive forces are transferred to bearing surfaces at opposed ends of the yoke where the draft gear is housed.
Adjacent freight cars are separated in accordance with standard specifications which includes an allowance for a specified yoke length. In accordance with applicable AAR standards, typically, E-type and F-type yokes, respectively, may have a length of 41⅛″ or 37½″.